CFD Modeling of Drilling Cuttings Transport Using Foam in Horizontal Well Condition

Efficient drilling cuttings transport is one of the most important parameters affecting drilling rate of wells. Foam has a great potential to reduce drilling problems compared to conventional well drilling fluids due to its unique properties such as low density and high viscosity. Proper description of foam behavior enables us to improve the performance of foam for hole- cleaning. In this paper, cuttings transport using foam was studied using a computational fluid dynamics approach. In this study the Eulerian multi-phase model was used to describe cuttings-fluid mixture flow. Foam rheology was expressed by the non-Newtonian power law model. Effects of foam quality and injection velocity, cuttings size, pipe eccentricity and rotational speed of drillpipes were studied. Modeling results were also compared with experimental data. Results showed that increase of foam quality improved hole-cleaning operation mainly due to the enhanced foam viscosity. Increase of foam injection velocity led to a reduction in in-situ cuttings concentration. This was due to the foam capability to destruct stationary cuttings bed. Accordingly, as foam injection velocity increased from 3 to 5 ft/s, cuttings concentration decreased by 1.3 times. Also, an increase in the size of the cuttings caused a poor well cleaning. It was found that pipe eccentricity resulted in the accumulation of cuttings in the wellbore annulus. But, increase of the drillpipe rotational speed provided a better hole-cleaning, so that by increasing the rotational speed to 40 RPM, cuttings concentration decreased by 1.8 and 1.4 times in concentric and eccentric pipe, respectively.